1. Field of the Invention
The present invention relates to an illumination unit having a plurality of light-emitting elements, an endoscope having this illumination unit, and an illumination probe which has this illumination unit and can be inserted into an endoscopic channel.
2. Description of the Related Art
In general, to obtain an excellent observation image, an endoscope has an illumination unit which illuminates an observation target with illumination light. The illumination unit has an illumination section that emits the illumination light and an optical system. The illumination section is, e.g., a halogen lamp or a xenon lamp. Such an illumination section is arranged in a light source device connected with an endoscope. Further, the optical system has a light guide fiber and an illumination window arranged in, e.g., the endoscope. The illumination light emitted from the illumination section is led to a distal end portion of an insertion section of the endoscope through an optical system, e.g., the light guide fiber or the like from the light source device to illuminate the observation target through the optical system, e.g., the illumination window.
Furthermore, in recent years, the illumination unit having the illumination section is arranged at the distal end portion of the insertion section. In this case, the illumination section is, e.g., a light-emitting element such as an LED which illuminates the observation target with illumination light. This light-emitting element serves as a light source. Moreover, in this case, the endoscope does not need to have a built-in light guide fiber. Therefore, a diameter and a weight of the insertion section are reduced. Additionally, the illumination section, e.g., a halogen lamp or a xenon lamp does not have to be arranged in the light source device. As described above, a configuration of the endoscope and a configuration of a peripheral device of the endoscope, e.g., the light source device can be simplified.
For example, Jpn. Pat. Appln. KOKAI Publication No. 2002-51971 discloses an endoscope comprising illumination means at a scope end, the endoscope being configured to increase the amount of illumination light. In this endoscope, when a plurality of light-emitting elements are arranged on a surface of a distal end portion of an insertion section, the amount of illumination light increases.
Further, for example, Jpn. Pat. Appln. KOKAI Publication No. 2007-252843 discloses an endoscope which effectively utilizes light-emitting diode light as illumination light and reduces a cost without optical loss caused due to use of an illumination light lens. In this endoscope, when a reflection plane is arranged between a light-emitting element and a surface of a distal end portion, desired light distribution characteristics and illumination suitable for various arrangements can be obtained.